The present disclosure is directed to a method for fabricating a semiconductor device, and more particularly, to a method for fabricating a semiconductor device that can improve flatness.
With the increasing integration of semiconductor devices, contact plugs are formed to electrically connect interconnections alternatingly stacked with insulating layers in-between. The contact plugs may be formed by forming contact holes in the insulating layers, filling a conductive material in the contact holes and performing a planarizing process for electrical isolation between the contact plugs.
Then, the contact plugs may be formed on a semiconductor substrate having differing levels of integration for different respective regions. In other words, in a semiconductor device including a memory cell region and a peripheral circuit region, contact plugs may have a higher density in the memory cell region than in the peripheral circuit region.
Thus, in the case where the density of the contact plugs differs by region, flatness may differ by region due to the planarizing process that forms the contact plugs. That is, a height difference between predetermined regions may be generated.